(1) Field of the Invention
This invention relates to purlin bridging.
(2) Prior Art
Rolled steel purlins commonly used in the framing of buildings usually require to be bridged at intervals to maintain their parallelism and prevent twisting. A well known purlin is rolled to the form of a vertical web with oppositely directed flanges extending from top and bottom, the distal portion of the upper flange being down-turned, that of the bottom flange being up-turned. The web is usually formed at intervals with pairs of holes, and holes aligned with these are formed in the top and bottom flanges also, these holes being provided to enable the bolting to the purlins of other structural members of the building, including the connection of bridging members between succeeding purlins.
The bridging members hitherto used are normally channel sections with connector fittings attached to their ends, and they have the disadvantages of being costly to manufacture and inconvenient and laborious to connect to the purlins and, unless they are formed of heavy gauge sheet metal, they are likely to fail under stress. Furthermore, they are bulky to store and transport.